1. Field of the Invention
The present invention relates to an image reading apparatus having a multi-crop function.
2. Description of the Related Art
There has been known a multi-crop function in which, in the case where small size originals, such as business cards, postcards, or photos, are to be read, multiple originals are placed on an original table and scanned and read in batch to crop an image corresponding to each original. There has also been known an image reading apparatus having such multi-crop function.
For example, there has been proposed an apparatus which detects the number of originals and their respective positions by pre-scan, scans the originals one by one, and displays how many originals have been scanned before the currently-scanned original, so as to enable a user to recognize an image reading state (see Japanese Unexamined Patent Publication No. 2003-219085, for example). There has also been proposed an apparatus that controls the order of cropping an image according to the original size of a cropped image, the position of the original, a size of a printing sheet used to print the original, and the type of the printing sheet, even if originals of different sizes and different types are simultaneously placed (see Japanese Unexamined Patent Publication No. 2007-013378, for example). There has also been proposed an apparatus that compares the input number of originals and the detected number of originals, and displays the comparison result, in order to correctly detect the number of images that the user desires to crop and to read these images (see Japanese Unexamined Patent Publication No. 2007-020122, for example).
One of useful methods out of methods for cropping an image corresponding to each original is to extract a border between an original and an area outside of the original on the premise that the original has a rectangular shape and has a white or light tone edge. To clearly read the border, the area outside of the original is configured to be read as black or dark tone. For example, it is supposed that there is an image reading apparatus of a type that emits light from below an original surface and reads reflection light diffusely reflected on the original surface. When reading an original, the image reading apparatus generally scans the original by holding the original from top using an original cover. However, when a multi-crop process is selected, the image reading apparatus notifies the user that the original has to be scanned with the original cover being left open. When the original is scanned with the original cover being left open, diffused reflection of emitted light is not generated on the area outside of the original. On the other hand, reflection light diffusely reflected on the original surface is returned to the white or light tone edge of the original. A difference in contrast is generated between an image to be read on the edge of the original to which reflection light is returned and an image to be read on the area outside of the original. The border of the original can be determined on the basis of the contrast. Notably, in place of the way in which a batch scan is performed with the original cover being left open, the lower surface of the original cover may be formed to have a black color or dark tone to enable absorption of light, or the lower surface of the original cover may be formed such that diffused reflection hardly occurs, for example, formed from a mirror-finished metal surface.
A typical original such as an office document includes characters, graphics, or images on a white sheet, and there is a margin on an edge thereof. However, this is not always the case for particularly originals to which a multi-crop scan is to be performed. For example, photos without borders or cards using colored sheets do not always have a white or light tone edge, although they are rectangle.